66691872 has 144 divisors (see below), whose sum is σ = 209139840. Its totient is φ = 20030976.

The previous prime is 66691853. The next prime is 66691897. The reversal of 66691872 is 27819666.

66691872 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a tau number, because it is divible by the number of its divisors (144).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 175779 + ... + 176157.

It is an arithmetic number, because the mean of its divisors is an integer number (1452360).

Almost surely, 2^66691872 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 66691872, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (104569920).

66691872 is an abundant number, since it is smaller than the sum of its proper divisors (142447968).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

66691872 is a wasteful number, since it uses less digits than its factorization.

66691872 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 455 (or 444 counting only the distinct ones).

The product of its digits is 217728, while the sum is 45.

The square root of 66691872 is about 8166.5091685493. The cubic root of 66691872 is about 405.5312279090.

The spelling of 66691872 in words is "sixty-six million, six hundred ninety-one thousand, eight hundred seventy-two".